This invention relates to nozzles for dispensing fuels such as gasoline which have easier operation and more accurate control of the amount of fuel being dispensed.
Hand-operated fuel dispensing nozzles are widely used in service stations in the transfer of fuel into the tank of a vehicle such as an automobile. In order to achieve high delivery flow rates, fluid pressure in the delivery circuit is usually maintained at a relatively high level and this requires relatively high manual effort for actuation of the dispensing nozzle. An additional problem often encountered by a person operating such a dispensing nozzle is a variation in pressure which occurs between the open and closed conditions of the dispensing valve accompanied by a corresponding fluctuation in the required operating force, making it particularly difficult to modulate the dispensing nozzle at low flow rates.
It is important to be able to control the flow rate and cut-off of a fuel dispensing nozzle. As costs have increased, a penny's worth of fuel has become more and more difficult to meter, since it represents a diminishing quantity. It has thus become increasingly difficult to prevent overshooting of the desired dollar amount of a purchase. Often, a customer orders an even dollar amount of fuel and is dissatisfied with being charged for fuel in excess of that which he has ordered. A policy of forgiving the charge of a few extra cents to a customer is undesirable since the accumulation of a few cents for many customers can amount to a significant dollar loss. Moreover, a system which must tolerate such shortages also has the potential for employee fraud.
The difficulties involved in the use of a dispensing nozzle outlined above are particularly acute in self-service gasoline stations. In self-service installations, the general patronage will contain people of widely differing motor skills, dexterity, grip, and familiarity with dispensing equipment.